CDL Air Brake Leak Test – Step by Step Here’s how to correctly perform the air brake leak test, CDL exactly how examiners want to see it: 🔹 Static Leak Test Release the parking brake Let the system stabilize Set a 1-minute timer Firmly apply the brake pedal ✅ You should not lose more than 3 PSI in one minute 🔹 Low Air Warning Test Begin fanning the brakes ✅ Light and buzzer must activate before 55 PSI 🔹 Emergency Brake Test Continue fanning the brakes ✅ Parking brake must pop out between 20–4